I currently hate the search feature because it won't let you type something that's two letters. Such as XP, whether it is for Windows or Athlon. You should limit nothing.
I understand the problem you are having with this but it's really a vB software limitation, not one we have imposed. I do have one tip for you though, unlike most vB based forums out there I have made sure ours is completely google-spider friendly, so you can go to google and search for any terms like this: "KEYWORDS site:techspot.com" Let me know if that is of any help.